Since the Austrian scientist Reinitzer first synthesized a liquid crystal in 1888, the actual development of the liquid crystal industry is in the recent more than 30 years; since liquid crystal display materials have obvious advantages, such as a low drive voltage, a small power consumption, high reliability, a great display information amount, color display, no flicker, a capability of achieving panel display, etc., both liquid crystal monomers and liquid crystal displays have gone through a huge development, and liquid crystal monomers have been used in the synthesis of more than 10,000 kinds of liquid crystal materials, wherein there are thousands of common liquid crystal display materials, and by the classification according to the characteristics of the central bridge bond and rings of liquid crystal molecules, there are mainly biphenyl liquid crystals, phenyl cyclohexane liquid crystals, ester liquid crystals, alkynes, difluoromethoxy bridge types, ethane types and heterocyclic types. The liquid crystal display is also developed from TN and STN of black and white small screen in 30 years ago to the current TN-TFT, VA-TFT, IPS-TFT, PDLC of scale color screen, etc.
New liquid crystal display modes mainly include optical compensation bending mode (OCB), coplanar transformation liquid crystal display (IPS), vertical alignment mode (VA), axisymmetric microstructure liquid crystal display (ASM), multi-domain twisted liquid crystal display, etc.
In the various display modes, liquid crystal cells have different designs and different driving methods, and the orientations of liquid crystal molecular directors with respect to glass substrates are different, wherein in the optical compensation bending mode (OCB) and the coplanar transformation liquid crystal display (IPS), liquid crystal molecular directors are parallel to the direction of the glass substrates, while in the vertical alignment mode (VA) and the axisymmetric microstructure liquid crystal display (ASM), the liquid crystal molecular directors are perpendicular to the direction of the glass substrates in the absence of an electric field.
With regard to the IPS of the parallel arranged mode, the dielectric anisotropy (Δε) of the crystal may be either positive or negative.
In the vertical alignment mode (VA), all liquid crystal molecules in a null field are perpendicular to the direction of the glass substrates and parallel to a vertical incident light. When a polarizer is orthogonal, a good dark state is shown; therefore, this kind of device has a good contrast, and the dielectric anisotropy (Δε) of the crystal used has to be negative. The optical anisotropy (Δn) of the crystal, the thickness (d) of the liquid crystal cell and the wavelength (λ) of the incident light barely affect the contrast. The response time of the vertical alignment mode (VA) is much shorter than that of a twist-type device and is about half of that. Under the influence of an applied voltage, a VA device mainly produces a bending deformation of liquid crystal molecules, ECB produces a splay deformation of liquid crystal molecules, and the twisted display produces a twist deformation of liquid crystal molecules; the response times thereof are also inversely proportional to bending, splay, and twist elastic constants, respectively, because in general cases for most liquid crystals, the bending elastic constant of liquid crystal is greater than the splay elastic constant and the splay elastic constant is greater than the twist elastic constant, which is also the reason why the VA device has a faster response time.
In Patent US 20150259602, the following compound is disclosed:

wherein R′ and R″ represent alkyl groups. Since the presence of the two side fluorines and the rigid structure dibenzofuran in the molecule limits the deflection between the two benzene rings, this type of compound has a higher absolute value of dielectric anisotropy and a very high birefringence. However, also because of the presence of the rigid dibenzofuran ring, such an alkyl-substituted liquid crystal compound has a poorer intersolubility and readily precipitates at low temperatures. In order to enable the performance of a display device to be closer to ideal, people have always been working to study new liquid crystal compounds, which allows the performances of liquid crystal compounds and display devices to continuously advance.